CN111905779B - Multi-metal fluoride compound catalyst and preparation method and application thereof - Google Patents

Multi-metal fluoride compound catalyst and preparation method and application thereof Download PDF

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CN111905779B
CN111905779B CN202010878176.2A CN202010878176A CN111905779B CN 111905779 B CN111905779 B CN 111905779B CN 202010878176 A CN202010878176 A CN 202010878176A CN 111905779 B CN111905779 B CN 111905779B
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metal fluoride
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CN111905779A (en
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韩文锋
吴森
刘兵
余厚霖
王传钊
贾忠盛
陈爱民
唐浩东
李瑛�
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Zhejiang University of Technology ZJUT
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/06—Halogens; Compounds thereof
    • B01J27/138—Halogens; Compounds thereof with alkaline earth metals, magnesium, beryllium, zinc, cadmium or mercury
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/28—Regeneration or reactivation
    • B01J27/32—Regeneration or reactivation of catalysts comprising compounds of halogens
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
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    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/02—Heat treatment
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Abstract

The invention discloses a preparation method and application of a multi-metal fluoride compound catalyst. The preparation process of the catalyst comprises the steps of dissolving and stirring by a hydrothermal method, sealing and drying, centrifugally washing and drying to prepare BaF 2 The multi-metal fluoride compound catalyst which is used as a main catalyst and takes fluoride corresponding to any two metals of Sr, ca, zr, la, ce, pr and Sm and any one metal of Cu, zn and Ni as an auxiliary catalyst is applied to the reaction of preparing the fluorine-containing olefin by removing HCl from the gas phase of the fluorine-containing chloroalkane, and the multi-metal fluoride catalyst shows extremely high selectivity and stability. The catalyst of the invention has the advantages of low reaction temperature, good stability, high selectivity, low cost, strong reproducibility and the like.

Description

Multi-metal fluoride compound catalyst and preparation method and application thereof
Technical Field
The invention belongs to the technical field of catalyst preparation, and particularly relates to a multi-metal fluoride compound catalyst, a preparation method and application thereof, particularly application of the multi-metal fluoride compound catalyst in preparation of vinylidene fluoride by catalytic cracking of 1, 1-difluoro-1-chloroethane to remove HCl, and the multi-metal fluoride compound catalyst has the advantages of low reaction temperature, good stability, high selectivity, low cost, strong reproducibility and the like.
Background
BaF 2 Having a certain acidic site and having the strongest affinity for Cl or for chlorineThe adsorption is strongest, so the selectivity of the main product vinylidene fluoride (VDF) is high, but the stability is poor. And other metals with high activity and stability are doped, so that a solid solution can be formed, and the interaction is enhanced, so that the catalyst has high activity and high selectivity. It has good application prospect in the field of selective dehydrochlorination.
1, 1-difluoro-1-chloroethane (HCFC-142 b) is a compound of formula CH 3 -CClF 2 Hydrochlorofluorocarbons (HCFCs) of (i) are the leading industrial raw material for the production of polyvinylidene fluoride (PVDF) monomer vinylidene fluoride (VDF). Since the early 1990 s, the content of HCFC-142b in the atmosphere has been steadily increasing, and at present, HCFC-142b can be used as a raw material to produce polyvinylidene fluoride to reduce the content of the atmosphere.
The thermal cracking of HCFC-142b must be carried out at high temperature, which easily causes the occurrence of carbon deposition coking, side reaction and disproportionation reaction, thereby affecting the yield. When the catalyst is added, the reaction energy barrier of HCFC-142b dehydrochlorination is reduced, the reaction temperature is greatly reduced, and the method is an effective and environment-friendly way for producing VDF. At present, various defects exist in catalysts for removing HCl by catalytic cracking R-142b, such as that an activated carbon catalyst is easy to be activated and difficult to regenerate, a metal oxide is easy to react with hydrogen chloride and quickly deactivated, and the like, so that the development of a chlorine-resistant catalyst in the reaction has important significance.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention aims to provide a multi-metal fluoride compound catalyst and a preparation method and application thereof. The method has the advantages of short preparation period, high yield and simple operation. The prepared catalyst is a multi-metal fluoride compound catalyst. The catalyst synthesized by the method has good catalytic activity and stability in the reaction of preparing vinylidene fluoride by removing HCl through catalytic cracking of 1, 1-difluoro-1-chloroethane.
The multi-element metal fluoride compound catalyst is characterized in that the compound catalyst is BaF 2 As main catalyst, MF X Is used as a cocatalyst and is prepared by a hydrothermal method, wherein M is three metals including Sr, ca, la, ce and SAny two of m, pr and Zr and any one of Cu, zn and Ni.
The preparation method of the multi-metal fluoride compound catalyst is characterized by comprising the following steps:
1) Dissolving barium nitrate and nitrate corresponding to metal of a cocatalyst in deionized water, adding a certain amount of citric acid, violently stirring for 25-35min, adding a fluorinating agent, and stirring for 2.5-3.5h to obtain a precipitation mixed solution;
2) Transferring the precipitation mixed solution obtained in the step 1) to a hydrothermal kettle, sealing, performing hydrothermal treatment, centrifugally washing, and drying to obtain the multi-metal fluoride composite catalyst.
The preparation method of the multi-metal fluoride compound catalyst is characterized in that the feeding molar ratio of any metal of the cocatalyst in the step 1) to barium is respectively 0.01-2.
The preparation method of the multi-metal fluoride compound catalyst is characterized in that the fluorinating agent in the step 1) is ammonium fluoride, ammonium fluoroborate or ammonium hexafluorosilicate.
The preparation method of the multi-metal fluoride compound catalyst is characterized in that the citric acid and BaF in the step 1) 2 The feeding molar ratio of (1) is 0.5-4.
The preparation method of the multi-element metal fluoride compound catalyst is characterized in that the hydrothermal kettle in the step 2) is a hydrothermal kettle containing a Teflon lining.
The preparation method of the multi-element metal fluoride composite catalyst is characterized in that the hydrothermal treatment in the step 2) is performed for 20-26h under the condition of 170-190 ℃, preferably for 24h under the condition of 180 ℃ in a sealed manner, and the multi-element metal fluoride composite catalyst is centrifugally washed for 2-4 times by using deionized water, preferably for 3 times; the drying temperature is 90-110 deg.C, the drying time is 10-14h, preferably 100 deg.C for 12h.
The multi-element metal fluoride compound catalyst is applied to the HCl removal reaction of 1, 1-difluoro-1-chloroethane catalytic cracking.
The application is characterized in that the temperature for removing HCl through catalytic cracking of 1, 1-difluoro-1-chloroethane is 250-500 ℃, the reaction pressure is normal pressure, and the reaction is carried out in a fixed bed reactor.
By adopting the technology, compared with the prior art, the invention has the following beneficial effects:
the multi-element metal fluoride compound catalyst obtained by adopting the limiting technology has the advantages of low reaction temperature, good stability, high selectivity, low cost and the like, and can be used for preparing vinylidene fluoride by catalyzing and cracking and removing HCl by the aid of 1, 1-difluoro-1-chloroethane.
Detailed Description
The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.
Example 1
1.000mol Ba (NO) 3 ) 2 ，1.000molCa(NO 3 ) 2 ，0.125molZn(NO 3 ) 2 ·6H 2 O and 0.125mol La (NO) 3 ) 3 ·6H 2 Dissolving O in 150mL deionized water, adding 4mol citric acid, vigorously stirring for 35min, and adding 4.625mol NH 4 F is slowly added and stirred for 2.5h, then the precipitate mixed liquor is sealed by a hydrothermal kettle for treatment at 180 ℃ for 24h, is taken out and washed by water for 3 times, is put into a drying oven for drying at 100 ℃ for 12h to obtain a catalyst sample, and is sieved by a sample-separating sieve of 20-40 meshes after tabletting.
The multi-element metal fluoride catalyst prepared by the method is used for catalyzing 1, 1-difluoro-1-chloroethane (HCFC-142 b) to crack to prepare 1, 1-difluoroethylene (VDF), and the reaction formula is as follows:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: the catalyst is filled into a fixed bed reactor, the filling amount of the catalyst is 3mL, and N is introduced 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 250 ℃. A sample is taken for analysis after 30h of reaction, and the result is as follows: the conversion of reactant 1, 1-difluoro-1-chloroethane was 86.5%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 97.0%.
Example 2
1.000mol Ba (NO) 3 ) 2 ，0.500molSr(NO 3 ) 2 ，0.031mol Zn(NO 3 ) 2 ·6H 2 O and 0.125mol Ce (NO) 3 ) 3 ·6H 2 Dissolving O in 150mL deionized water, adding 2mol citric acid, stirring vigorously for 30min, and adding 3.437mol NH 4 F, slowly adding the precipitate into the mixture, stirring the mixture vigorously for 3 hours, then carrying out hydrothermal treatment on the precipitate mixed solution for 26 hours at the temperature of 170 ℃ in a sealed manner by using a hydrothermal kettle, taking out the precipitate mixed solution, washing the precipitate mixed solution for 4 times by using water, putting the precipitate mixed solution into a drying oven, drying the precipitate mixed solution for 14 hours at the temperature of 110 ℃ to obtain a catalyst sample, tabletting the catalyst sample, and screening the catalyst sample by using a sample separation sieve of 20-40 meshes.
The multi-element metal fluoride catalyst prepared by the method is used for catalyzing 1, 1-difluoro-1-chloroethane (HCFC-142 b) to crack to prepare 1, 1-difluoroethylene (VDF), and the reaction formula is as follows:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: filling the catalyst into a fixed bed reactor, wherein the filling amount of the catalyst is 3mL, and introducing N 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 310 ℃. A sample is taken for 35h of reaction analysis, and the result is as follows: the conversion of reactant 1, 1-difluoro-1-chloroethane was 85.9%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 98.0%.
Example 3
1.000mol Ba (NO) 3 ) 2 ，1.000molSr(NO 3 ) 2 ，0.063molZn(NO 3 ) 2 ·6H 2 O and 0.010mol Pr (NO) 3 ) 3 ·6H 2 Dissolving O in 150mL deionized water, adding 2mol citric acid, stirring vigorously for 25min, and adding 4.156mol NH 4 F, slowly adding the precipitate into the mixture, stirring the mixture vigorously for 3.5h, then sealing the precipitate mixed solution by using a hydrothermal kettle, carrying out hydrothermal treatment for 22h at 190 ℃, taking out the precipitate mixed solution, washing the precipitate mixed solution by using water for 2 times, putting the precipitate mixed solution into a drying oven, drying the precipitate mixed solution for 10h at 90 ℃ to obtain a catalyst sample, tabletting the catalyst sample, and screening the catalyst sample by using a sample separation sieve of 20-40 meshes.
The multi-element metal fluoride catalyst prepared by the method is used for catalyzing 1, 1-difluoro-1-chloroethane (HCFC-142 b) to crack to prepare 1, 1-difluoroethylene (VDF), and the reaction formula is as follows:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: filling the catalyst into a fixed bed reactor, wherein the filling amount of the catalyst is 3mL, and introducing N 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 300 ℃. A sample is taken for 35h of reaction, and the result is as follows: the conversion of reactant 1, 1-difluoro-1-chloroethane was 89.5%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 96.4%.
Example 4
1.000mol Ba (NO) 3 ) 2 ，1.000molSr(NO 3 ) 2 ，0.125molNi(NO 3 ) 2 ·6H 2 O and 0.010mol Ce (NO) 3 ) 3 ·6H 2 Dissolving O in 150mL deionized water, adding 1mol citric acid, stirring vigorously for 30min, and adding 4.280mol NH 4 F, slowly adding the precipitate into the mixture, stirring the mixture vigorously for 3 hours, then carrying out hydrothermal treatment on the precipitate mixed solution for 20 hours at 180 ℃ by using a hydrothermal kettle, taking out the precipitate mixed solution, washing the precipitate mixed solution for 4 times by using water, putting the precipitate mixed solution into a drying oven, drying the precipitate mixed solution for 14 hours at 90 ℃ to obtain a catalyst sample, and sieving the catalyst sample by using a sample sieve of 20-40 meshes after tabletting.
The multi-element metal fluoride catalyst prepared by the method is used for catalyzing 1, 1-difluoro-1-chloroethane (HCFC-142 b) to crack to prepare 1, 1-difluoroethylene (VDF), and the reaction formula is as follows:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: catalyst loadingIn a fixed bed reactor, the filling amount of the catalyst is 3mL, and N is introduced 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 320 ℃. A sample is taken for 35h of reaction, and the result is as follows: the conversion of reactant 1, 1-difluoro-1-chloroethane was 90.5%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 99.6%.
Example 5
1.000mol of Ba (NO) 3 ) 2 ，0.750mol Sr(NO 3 ) 2 ，0.010mol Cu(N O 3 ) 2 ·6H 2 O and 0.125mol Sm (NO) 3 ) 3 ·6H 2 Dissolving O in 150mL deionized water, adding 0.5mol citric acid, stirring vigorously for 32min, and adding 3.895mol NH 4 F, slowly adding the precipitate into the mixture, stirring the mixture vigorously for 2.8 hours, then sealing the precipitate mixed solution by using a hydrothermal kettle, carrying out hydrothermal treatment for 22 hours at 190 ℃, taking out the precipitate mixed solution, washing the precipitate mixed solution for 3 times by using water, putting the precipitate mixed solution into a drying oven, drying the precipitate mixed solution for 14 hours at 110 ℃ to obtain a catalyst sample, tabletting the catalyst sample, and screening the tabletted catalyst by using a sample separating sieve of 20-40 meshes.
The multi-element metal fluoride catalyst prepared by the method is used for catalyzing 1, 1-difluoro-1-chloroethane (HCFC-142 b) to crack to prepare 1, 1-difluoroethylene (VDF), and the reaction formula is as follows:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: the catalyst is filled into a fixed bed reactor, the filling amount of the catalyst is 3mL, and N is introduced 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 500 ℃. A sample is taken for analysis after 40 hours of reaction, and the result is as follows: the conversion of reactant 1, 1-difluoro-1-chloroethane was 98.5%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 94.6%.
Example 6
1.000mol of Ba (NO) 3 ) 2 ，1.000mol Ca(NO 3 ) 2 ，0.013mol Cu(N O 3 ) 2 ·6H 2 O and 0.063mol Ce (NO) 3 ) 3 ·6H 2 Dissolving O in 150mL of deionized water, and then adding 0.8mol of citric acidStirring vigorously for 30min, and adding 1.054mol of NH 4 BF 4 Slowly adding the mixture into the mixture, stirring the mixture vigorously for 3 hours, then sealing the precipitate mixed solution by using a hydrothermal kettle, carrying out hydrothermal treatment for 26 hours at the temperature of 170 ℃, taking out the precipitate mixed solution, washing the precipitate mixed solution by using water for 2 times, putting the precipitate mixed solution into a drying oven, drying the precipitate mixed solution for 14 hours at the temperature of 110 ℃ to obtain a catalyst sample, tabletting the catalyst sample, and screening the catalyst sample by using a sample separating sieve of 20-40 meshes.
The multi-element metal fluoride catalyst prepared by the method is used for catalyzing 1, 1-difluoro-1-chloroethane (HCFC-142 b) to crack to prepare 1, 1-difluoroethylene (VDF), and the reaction formula is as follows:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: filling the catalyst into a fixed bed reactor, wherein the filling amount of the catalyst is 3mL, and introducing N 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 320 ℃. A sample is taken for 35h of reaction, and the result is as follows: the conversion of reactant 1, 1-difluoro-1-chloroethane was 88.8%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 98.9%.
Example 7
1.000mol of Ba (NO) 3 ) 2 ，1.000mol Sr(NO 3 ) 2 ，0.063mol Ni(N O 3 ) 2 ·6H 2 O and 0.022molLa (NO) 3 ) 3 ·6H 2 Dissolving O in 150mL deionized water, adding 1.8mol citric acid, stirring vigorously for 30min, and adding 1.048mol NH 4 BF 4 Slowly adding the mixture into the kettle, stirring the mixture for 3 hours, sealing the precipitate mixed solution by a hydrothermal kettle at 180 ℃, carrying out hydrothermal treatment for 24 hours, taking out the precipitate mixed solution, washing the precipitate mixed solution for 3 times by water, putting the precipitate mixed solution into a drying oven, drying the precipitate mixed solution for 12 hours at 100 ℃ to obtain a catalyst sample, tabletting the catalyst sample, and sieving the catalyst sample by a sample sieve of 20-40 meshes.
The multi-element metal fluoride catalyst prepared by the method is used for catalyzing 1, 1-difluoro-1-chloroethane (HCFC-142 b) to crack to prepare 1, 1-difluoroethylene (VDF), and the reaction formula is as follows:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: filling the catalyst into a fixed bed reactor, and filling the catalystFilling amount of 3mL, introducing N 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 320 ℃. A sample is taken for 35h of reaction analysis, and the result is as follows: the conversion of reactant 1, 1-difluoro-1-chloroethane was 89.1%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 97.9%.
Example 8
1.000mol of Ba (NO) 3 ) 2 ，1.000molCa(NO 3 ) 2 ，0.013mol Ni(NO 3 ) 2 ·6H 2 O and 0.003mol Ce (NO) 3 ) 3 ·6H 2 O is dissolved in 150mL of deionized water, 1.0mol of citric acid is added, stirring is carried out vigorously for 28min, and 2.018mol (NH) of the solution is added 4 ) 2 Si F 6 Slowly adding the precipitate into the mixture, stirring the mixture vigorously for 3.2h, then sealing the precipitate mixed solution by using a hydrothermal kettle, carrying out hydrothermal treatment for 22h at 190 ℃, taking out the precipitate mixed solution, washing the precipitate mixed solution for 3 times by using water, putting the precipitate mixed solution into a drying oven, drying the precipitate mixed solution for 13h at 110 ℃ to obtain a catalyst sample, tabletting the catalyst sample, and screening the tabletted catalyst by using a sample separating sieve of 20-40 meshes.
The multi-element metal fluoride catalyst prepared by the method is used for catalyzing 1, 1-difluoro-1-chloroethane (HCFC-142 b) to crack to prepare 1, 1-difluoroethylene (VDF), and the reaction formula is as follows:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: filling the catalyst into a fixed bed reactor, wherein the filling amount of the catalyst is 3mL, and introducing N 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 450 ℃. A sample of the reaction was taken for 33h and analyzed, and the results were: the conversion of reactant 1, 1-difluoro-1-chloroethane was 94.7%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 98.0%.
Example 9
1.000mol of Ba (NO) 3 ) 2 ，1.000mol Sr(NO 3 ) 2 ，0.031mol Ni(N O 3 ) 2 ·6H 2 O and 0.003mol Zr (NO) 3 ) 4 ·6H 2 Dissolving O in 150mL of deionized water, and adding 1.2mol of citric acid for vigorous stirringStirring for 30min, then adding 2.037mol (NH) 4 ) 2 Si F 6 Slowly adding the mixture into the kettle, stirring the mixture for 3 hours, sealing the precipitate mixed solution by a hydrothermal kettle at 180 ℃, carrying out hydrothermal treatment for 24 hours, taking out the precipitate mixed solution, washing the precipitate mixed solution for 4 times by water, putting the precipitate mixed solution into a drying oven, drying the precipitate mixed solution for 12 hours at 100 ℃ to obtain a catalyst sample, tabletting the catalyst sample, and sieving the catalyst sample by a sample sieve of 20-40 meshes.
The multi-element metal fluoride catalyst prepared by the method is used for catalyzing 1, 1-difluoro-1-chloroethane (HCFC-142 b) to crack to prepare 1, 1-difluoroethylene (VDF), and the reaction formula is as follows:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: filling the catalyst into a fixed bed reactor, wherein the filling amount of the catalyst is 3mL, and introducing N 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 320 ℃. A sample is taken for 35h of reaction analysis, and the result is as follows: the conversion of reactant 1, 1-difluoro-1-chloroethane was 97.5%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 95.8%.
Example 10
The reacted catalyst was air-muffle-fired at a reaction temperature of 320 c in example 4 for 4 hours to remove carbon deposits on the surface of the catalyst, thereby regenerating the catalyst, and then used again for the preparation of 1, 1-difluoroethylene (VDF) by catalytic cracking of 1, 1-difluoro-1-chloroethane (HCFC-142 b), and was reused 5 times, with the following reaction formula:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: filling the catalyst into a fixed bed reactor, wherein the filling amount of the catalyst is 3mL, and introducing N 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 320 ℃. Sampling and analyzing for 35h of reaction, and obtaining the catalytic results of 5 times of recovered regenerated catalysts as follows: the conversion of reactant 1, 1-difluoro-1-chloroethane was 90.2%, 90.8%, 91.2%, 89.9%, 90.3%, and the selectivity of product 1, 1-difluoroethylene (VDF) was 99.2%, 98.2%, 99.6%, 99.6 percent and 98.3 percent. And both the conversion rate and the selectivity can be kept for more than 50h without being substantially inactivated.
Example 11
The reacted catalyst was air-muffle-fired at a reaction temperature of 310 ℃ for 6 hours in example 2 to remove carbon deposits on the surface of the catalyst, thereby regenerating the catalyst, which was then regenerated after 5 recoveries for use in catalyzing the cracking of 1, 1-difluoro-1-chloroethane (HCFC-142 b) to produce 1, 1-difluoroethylene (VDF), according to the following reaction formula:
CF 2 ClCH 3 →CF 2 ＝CH 2 +HCl
the reaction conditions are as follows: the catalyst is filled into a fixed bed reactor, the filling amount of the catalyst is 3mL, and N is introduced 2 Mixed gas with HCFC-142b, N 2 The flow rate is 20mL/min, the flow rate of HCFC-142b is 20mL/min, and the space velocity of HCFC-142b is 400h -1 The reaction temperature was 310 ℃. Sampling and analyzing for reaction for 35h, and obtaining 5 recycling regeneration results: the conversion of reactant 1, 1-difluoro-1-chloroethane was 83.5%, 84.6%, 85.9%, 85.7%, 85.6%, the selectivity of product 1, 1-difluoroethylene (VDF) was 97.5%, 98.0%, 98.9%, 98.3%, 98.6%. And both the conversion rate and the selectivity can be kept for more than 45h without being substantially inactivated.
The statements in this specification merely set forth a list of implementations of the inventive concept and the scope of the present invention should not be construed as limited to the particular forms set forth in the examples.

Claims (10)

1. The multi-metal fluoride compound catalyst is characterized in that the compound catalyst is BaF 2 As main catalyst, MF X The catalyst is a cocatalyst and is prepared by a hydrothermal method, wherein M is three metals including any two of Sr, ca, la, ce, sm, pr and Zr and any one of Cu, zn and Ni.
2. The method for preparing the multi-metal fluoride complex catalyst according to claim 1, comprising the steps of:
1) Dissolving barium nitrate and nitrate corresponding to metal of a cocatalyst in deionized water, adding a certain amount of citric acid, violently stirring for 25-35min, adding a fluorinating agent, and stirring for 2.5-3.5h to obtain a precipitation mixed solution;
2) Transferring the precipitation mixed solution obtained in the step 1) to a hydrothermal kettle, sealing, performing hydrothermal treatment, centrifugally washing, and drying to obtain the multi-metal fluoride composite catalyst.
3. The method for preparing the multi-metal fluoride composite catalyst according to claim 2, wherein the feeding molar ratio of any metal of the promoter to barium in the step 1) is 0.01-2.
4. The method for preparing the multi-metal fluoride composite catalyst according to claim 2, wherein the fluorinating agent in the step 1) is ammonium fluoride, ammonium fluoroborate or ammonium hexafluorosilicate.
5. The method for preparing the multi-metal fluoride composite catalyst according to claim 2, wherein the citric acid and BaF in the step 1) 2 The feeding molar ratio of (A) is 0.5-4.
6. The method for preparing the multi-metal fluoride composite catalyst according to claim 2, wherein the hydrothermal kettle in the step 2) is a hydrothermal kettle containing a teflon lining.
7. The preparation method of the multi-metal fluoride composite catalyst according to claim 2, wherein the sealed hydrothermal treatment in step 2) is performed for 20-26h in a hydrothermal kettle at 170-190 ℃, and the centrifugal washing is performed for 2-4 times by using deionized water; the drying temperature is 90-110 deg.C, and the drying time is 10-14h.
8. The method for preparing the multi-metal fluoride composite catalyst according to claim 2, wherein the sealed hydrothermal treatment in step 2) is performed for 24 hours in a hydrothermal kettle at 180 ℃, and the centrifugal washing is performed for 3 times by using deionized water; drying at 100 deg.C for 12h.
9. The use of the multi-metal fluoride composite catalyst of claim 1 in the catalytic cracking and HCl removal reaction of 1, 1-difluoro-1-chloroethane.
10. The use according to claim 9, characterized in that the temperature for catalytic cleavage of 1, 1-difluoro-1-chloroethane to remove HCl is 250-500 ℃, the reaction pressure is normal pressure, and the reaction is carried out in a fixed bed reactor.
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